A light emitting diode (LED) is widely used as the light source (load) of a lighting device of a vehicle. As a device for detecting failure such as disconnection of the LED, an LED disconnection detection device that supplies to the LED a pulse signal having such a pulse width that does not light the LED and detects the presence or absence of disconnection of the LED has been devised (see Patent Literature 1).
Further, an abnormality detection device of an LED lighting unit that determines an abnormality of the LED lighting unit before lighting the LED lighting unit has been devised (see Patent Literature 2).
Further, an LED abnormality detection device, including a pull-up circuit, that can detect disconnection by turning on a pull-up switching element of the pull-up circuit when a drive switching element is off and can detect short-to-power by turning off the pull-up switching element of the pull-up circuit when the drive switching element is off has been devised (see Patent Literature 3).